Carburetor



March 25, 1930. H. B. PETIT CARBURETOR Filed Dc. 3, 1926 I N VEN TOR.

B f A TTORNE Y.

another passage 9 chamber y discharges Patented Mar. 25, 1930.

UNITED STATES PATENT OFFICE HENRY B. PETIT, 0F DETROIT, MICHIGAN, ASSIGNOR TO GEORGE M. HOLLEY, OF

DETROIT, MICHIGAN CARBU'RETOR Application filed December 3, 1926. Serial No. 152,324.

This invention relates to an improved carburetor. The object of this carburetor is to provide means for providing the most suitable mixture ratio for the varying conditions of air flow and specifically to provide means whereby the ratio of fuel to the air can be increased conveniently at all air flows to meet the requirements of the engine without disturbing the most economical fuel adjustment for normal conditions.

The figure shows more or less diagrammatically a cross sectional elevation, all the parts being so arranged as to be visible in one plane. (Actually, in the manufacture of the device, the various nozzles and passages would be located in other planes).

In this figure, a is the air entrance, I; is the mixing chamber, a is the mixture outlet, 61 is a throttle valve located therein, f is the float and e is a float chamber connected to the casting containing the mixing chamber in the well known manner. '11 is anextension downward from the casting containing the mixing chamber in which extension the nozzles are arranged and by which. extension the float chamber is connected to the mixing chamtions is and also,with a group of orifices inarked 0. The seriespf perforations k are located at diflerent, levels and communicate with the atmosphere through the passage Z. The groupof orifices ocommunicate with the atmosphere through the passage m, as shown by the arrows. The nozzlej discharges 1nto the mixing chamber 1), being located at the point of maximum constriction (greatest a1r velocity). v i

The passage 2 providesthe low speed fuel for'running the engine, and-is connected with which supplies fuel through a restriction 1- to the chamber y. The fuel and air through 8 into the mixture outlet 0 adjacent to the lip of the throttle d. The chamber y is air bled at t, which is a fixed opening, and through u and z, the flow through which is controlled by the needle valve 4;. This needle yalve 4) thus constitutes the low speed adustment.

An additional high speed fuel passage n 1s provided. This passagem, is supplied with fuel independently of the fuel metered at the orifice g by the needle valve h.

The additional high speed fuel in n is regulated by the size of the plug 1:, but chiefly by the size of the fuel outlet w, which is smaller than m. This additional high speed fuel outlet is located in the air entrance at.

Operation.The provision of the additional high speed fuel orifice 'w, the passage 7 and restriction 0 is the chief novel feature in this carburetor. When running at closed which controls the orifice z. The operation of the main fuel nozzle j is as follows Fuel flows from 6 through the passage in j and discharges into the mixing chamber 6. Enroute it is atomized by air drawn in through m and 0 and subsequently as the speed of the engine increases, by air drawn in through Z and k.' A shoulder on the nozzle j prevents any direct communication between the two passages Z and m, except through the center passage By providing liberal openings to the passages Z k and m o it is obvious that the mixture at high air velocity will tend to become excessively lean, or to become over compensated as it is colloquially called, and this tendency is compensated for by the provision of the orifice w. It will be noted that theorifice w is located at a considerable distance (1" or more) above the level of the fuel in the float chamber e. There will therefore have to be a greater depression in a than 1" of gasoline before-the nozzle w comes into operation. The specific period in the operation of the engine at which increase, and the area of w is arranged to pression, however, in the air entrance a tends to increase progressively as the a1r speeds correct the above mentioned tendency of the fuel nozzle 7' to lean out.

When the choke valve (1 in the air entrance a is closed, as shown in the dotted lines, a very much larger depression is created in the airentrance a, andquite a large flow of fuel issues from w which acts as a primer. This ensures ample fuel for starting. It will also be noticed that a small movement of the choke valve a creates a slight depression in' the air entrance (1, so that such a movement of the choke valve a which would hardly disturb the flow through the nozzle j due to its atmospheric bleeding through l m 0 in, or the flow through p g and T, will cause a considerable fuel flow through w for the purpose of facilitating cold engine operation, and then I have provided delicate and convenient means for adjusting the mixture when driving away with a cold engine, and still retained the characteristic compensating feature of the air vented nozzle sion of nozzle 10 eliminates the necessity for unduly restricting the vents Z m by mechanical means which have heretofore been used.

of them. The size of the 4 orifices 0 should be #52 drill. The additional outlet w should be #60 drill, and w should be located '1'" above the level in the float chamber e. This articular installation I have found suitable or a Ford Model T engine.

What I claim is 1. In a plain tube carburetor having an air entrance, a mixing chamber of Venturi form and having a constant area, a constant level fuel supply chamber, a mixture outlet and a throttle valve therein, an air vented,

fuel nozzle discharging into the Venturi mixing chamber, an unvented nozzle discharging into an unrestricted portion of said air entrance, and a choke valve located therein on the atmospheric side of said additional nozzle, the unvented nozzle being located a considerable distance above the level in the constant level fuel supply chamber, and being independently fedtherefrom.

2. In a carburetor having an air entrance in free communication with the atmosphere, a mixing chamber of Venturi form and having a constant area, a constant level fuel sup-- ply, a mixture outlet and a throttle valve therein, an air vented fuel nozzle discharging into the throat of the Venturi, an unvented fuel nozzle discharging into an unrestricted portion of said air entrance and'hav- The provi-i ave found that the bore of the ing an independent communication with said fuel supply chamber whereby additional fuel may be fed in increasing quantities at the higher air velocities only.

3. In a plain tube carburetor having an air entrance, a mixing chamber of'Venturi form and having a constant area, a constant level fuel supply chamber, a mixture outlet and a throttle valve therein, an air vented fuel nozzle discharging into the Venturi cham her, an additional nozzle discharging into an unrestricted portion of said air entrance, the additional nozzle being located a considerable distance above the levelin the constant level fuel supply chamber, and being independently fed therefrom.

In testimony whereof I aflix my signature.

HENRY B. PETIT. 

